title: The incidence and aetiology of hospitalised community-acquired pneumonia among Vietnamese adults: a prospective surveillance in Central Vietnam.
abstract: BACKGROUND
  Lower respiratory tract infection (LRTI) including Community-acquired pneumonia (CAP) is a common infectious disease that is associated with significant morbidity and mortality. The patterns of aetiological pathogens differ by region and country. Special attention must be paid to CAP in Southeast Asia (SEA), a region facing rapid demographic transition. Estimates burden and aetiological patterns of CAP are essential for the clinical and public health management. The purposes of the study are to determine the incidence, aetiological pathogens, clinical pictures and risk factors of community-acquired pneumonia (CAP) in the Vietnamese adult population.
  
  
  METHODS
  A prospective surveillance for hospitalised adult CAP was conducted in Khanh Hoa Province, Central Vietnam. All adults aged ≥15 years with lower respiratory tract infections (LRTI) admitted to a provincial hospital from September 2009 to August 2010 were enrolled in the study. Patients were classified into CAP and non-pneumonic LRTI (NPLRTI) according to the radiological findings. Bacterial pathogens were identified from sputum samples by the conventional culture and polymerase chain reaction (PCR) for Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis; 13 respiratory viruses were identified from nasopharyngeal specimens by PCR.
  
  
  RESULTS
  Of all 367 LRTI episodes examined, 174 (47%) were CAP. Older age, the presence of underlying respiratory conditions, and higher index score of smoking were associated with CAP. The one-year estimated incidence of hospitalised adult CAP in our study population was 0.81 per 1,000 person years. The incidence increased considerably with age and was highest among the elderly. The case fatality proportion of hospitalised CAP patients was 9.8%. Among 286 sputum samples tested for bacterial PCR, 79 (28%) were positive for H. influenzae, and 65 (23%) were positive for S. pneumoniae. Among 357 samples tested for viral PCR, 73 (21%) were positive for respiratory viruses; influenza A (n = 32, 9%) was the most common.
  
  
  CONCLUSIONS
  The current adult CAP incidence in Vietnam was relatively low; this result was mainly attributed to the young age of our study population.
authors.affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Takahashi
authors.forename: Motoi
authors.initials: M
authors.lastname: Suzuki
authors.forename: Le Nhat
authors.initials: le N
authors.lastname: Minh
authors.forename: Nguyen Hien
authors.initials: NH
authors.lastname: Anh
authors.forename: Luu Thi Minh
authors.initials: LT
authors.lastname: Huong
authors.forename: Tran Vo Vinh
authors.initials: TV
authors.lastname: Son
authors.forename: Phan The
authors.initials: PT
authors.lastname: Long
authors.forename: Nguyen Thi Thuy
authors.initials: NT
authors.lastname: Ai
authors.forename: Le Huu
authors.initials: le H
authors.lastname: Tho
authors.forename: Konosuke
authors.initials: K
authors.lastname: Morimoto
authors.forename: Paul E
authors.initials: PE
authors.lastname: Kilgore
authors.forename: Dang Duc
authors.initials: DD
authors.lastname: Anh
authors.forename: Koya
authors.initials: K
authors.lastname: Ariyoshi
authors.forename: Lay Myint
authors.initials: LM
authors.lastname: Yoshida
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000382:microbiology / Q000821:virology; D005260:Female; D006760:Hospitalization; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction; D009305:Nasopharynx / Q000382:microbiology / Q000821:virology; D011446:Prospective Studies; D062486:Public Health Surveillance; D014744:Vietnam / Q000453:epidemiology